[MacPorts] #57448: i686-w64-mingw32-winpthreads and x86_64-w64-mingw32-winpthreads fail to compile

[MacPorts]

#57448: i686-w64-mingw32-winpthreads and  x86_64-w64-mingw32-winpthreads fail to
compile
-------------------------------------------------+-------------------------
  Reporter:  eviltwinskippy                      |      Owner:  mojca
      Type:  defect                              |     Status:  assigned
  Priority:  Normal                              |  Milestone:
 Component:  ports                               |    Version:  2.5.4
Resolution:                                      |   Keywords:  mingw
      Port:  i686-w64-mingw32-winpthreads        |  mingw-w64
  x86_64-w64-mingw32-winpthreads                 |
-------------------------------------------------+-------------------------

Comment (by kencu):

 Haven't seen this error before. I guess this linker does not like
 `-syslibroot`:
 {{{
 info:build libtool: link: /opt/local/bin/i686-w64-mingw32-gcc -shared
 src/.libs/libwinpthread_la-barrier.o src/.libs/libwinpthread_la-cond.o
 src/.libs/libwinpthread_la-misc.o src/.libs/libwinpthread_la-mutex.o
 src/.libs/libwinpthread_la-rwlock.o src/.libs/libwinpthread_la-spinlock.o
 src/.libs/libwinpthread_la-thread.o src/.libs/libwinpthread_la-ref.o
 src/.libs/libwinpthread_la-sem.o src/.libs/libwinpthread_la-sched.o
 src/.libs/libwinpthread_la-clock.o src/.libs/libwinpthread_la-nanosleep.o
 src/.libs/version.o   -L./fakelib -L/opt/local/lib  -Os -no-pthread
 -Wl,-headerpad_max_install_names -Wl,-syslibroot
 -Wl,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk
 -o .libs/libwinpthread-1.dll -Wl,--enable-auto-image-base -Xlinker --out-
 implib -Xlinker .libs/libwinpthread.dll.a
 info:build
 /opt/local/lib/gcc/i686-w64-mingw32/8.2.0/../../../../i686-w64-mingw32/bin/ld:
 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk:
 file not recognized: Is a directory
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/57448#comment:3>
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